I'll throw in my two cents and say Zombi 2 (though The Beyond is a very close 2nd). I just dig the slower zombies more so than the sprinters. And the crusty / deteriorated look of them makes this movie even more special to me.

I have to give another vote for The Beyond. I remember seeing the trailer many times when renting Palace Explosive tapes back in the 80s but it took a while to find a copy (damn local video stores with shitty Betamax selections), but when I did I was blown away. It's just flat out crazy and Fulci's most imaginative and stylish work. I was blown away again, years later when I watched the Grindhouse Releasing DVD for the first of many times, because it was the first time I got to see it uncut, so suddenly it was twice as awesomely gory, and they'd done such a fantastic job with the soundtrack. I couldn't help but play that sucker loud just to impress the neighbours with Frizzi's awesome score!!